Anno 1790

Army surgeon Johan Gustav Daadh gets offered the job of district police commissioner as he's seeing a patient home in Stockholm. He's also fallen in love with the chief constable's wife, Magdalena. When he realizes that Magdalena believes in him, he accepts the position and takes on his former patient, Simon Freund as his assistant.

A shop owner is found dead with a knife in his chest. A man has been caught red-handed, but Daadh isn't satisfied with what seems to be the obvious. He takes a different approach and reaches a surprising conclusion. One of his friends from the old days needs protection, but their meeting suddenly makes Daadh the focus of a vengeful woman's rage.

When Daadh goes to interrogate the person who printed pamphlets libeling the King, he finds the man murdered, his skull crushed in his own printing press. Daadh's investigation brings him in contact with a radical young French woman and with Marta Raxelius, who's convinced that Daadh killed her brother and will stop at nothing to get her revenge.

A cunning burglar is wreaking havoc in Stockholm. As the panic spreads, Daadh is under pressure to apprehend the masked thief, who's known to be dangerous and violent. He's offered help by the renowned hypnotist Cagliostori, who happens to be performing in the city. Daadh allows himself to be hynotized, unwittingly putting his own life in danger.

A bomb explodes in a packed coffee house. Daadh's investigation is interrupted by an order to stop the illegal church services held by a pietistic congregation, of which Simon Freund is secretly a member. When a priest from the state church is found burned to death, Daadh suspects a link between the two murders and that the perpetrator is in close proximity.

One of Daadh's old radical comrades is accused of treason and hung on the square. His body is supposed to go to Uppsala University for dissection by medical students. When the body disappears and two more murders take place, Daadh realizes that someone will kill indiscriminately to prevent him from uncovering a dangerous truth.